The present disclosure generally relates to a sealing device for use with ball valves. More specifically, the present disclosure relates to a differential pressure sealing device that utilizes the pressure created by the fluid passing through a piping system including a ball valve to pressurize a seating mechanism to aid in the operation of the ball valve.
Dirty, scaling fluids are fouling-up valves of all types in many industrial applications, including the refining, oil and gas production, geothermal power, chemical, pipeline and mining industries. The main weakness in most valves and in ball valves in particular, is that their seating designs do not keep particles and scale deposits out of the valve seat ring crevices, grooves, and cavities. This is particularly the case in trunnion style ball valves since their seat rings must be able to move axially to allow the line pressure to urge the seat onto the ball. When the seat ring cannot travel back and forth within the body end flange seat ring pocket, the seat cannot properly engage the ball seating surface and the valve cannot shut off, and/or the operating torques become excessive to the point of preventing the operation of the valve with resultant damage to the valve seats and its ball surface.
Trunnion ball valves, in particular, cannot be reliably used in many services such as with liquids and vapors that cause scale build-ups, and fluids that contain entrained minerals and solid materials such as sand, because such materials pack into the seat ring pocket spaces behind the seat rings of the valve and lock-it-up.